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Time capsule backups fail because disks aren't recognised - how to fix?

251 Views 3 Replies Latest reply: Jan 28, 2013 12:20 PM by LaPastenague RSS
Matt Bacon1 Level 1 Level 1 (15 points)
Currently Being Moderated
Nov 29, 2012 2:55 AM

Hi, all... I have a 500GB TC with a 2TB Western Digital drive attached, which I use for backing up three computers. My desktop iMac is connected to the TC by Ethernet cable, my laptop and my wife's laptop connect over wifi. The desktop and my wife's laptop back up to the WD drive. My laptop backs up to the TC internal drive.


Every few days (max, min is something like 1 day), I notice that the backups are all failing at the "Looking for backup disk" stage. That's both the iMac connected by Ethernet and the laptops on WiFi. The WiFi _signal_ is fine -- my laptops can see the network, browse to other destinations, download files at a good speed. The TC has a green light, and Airport Utility doesn't detect any issues.


But although the TC appears in the Finder Sidebar, it shows no disks. If I try to "Connect As" nothing happens.


I can resolve the issue by pulling the plug on the TC and re-powering it, and then doing the same with the WD disk. If I do that, both disks appear in the finder (with no need to "connect" to them) and backups proceed normally.


Backups can go on normally for anywhere between 8 hours and four days, but then I have to repeat the whole rigmarole to get them started again.


I'm beginning to suspect something to do with two backup processes over Ethernet and Wifi to two different backup disks "colliding" somehow and locking out the disks. I say this, because if I'm away for a week with my laptop, and my laptop does no backups to the TC in that week, then when I get back, the iMac is still backing up fine, even though five days is a long time compared to how often it seems to fail when all three machines are at home and backing up.


I don't want to have to keep pulling the plug, so does anyone have any ideas?


Many thanks!




  • LaPastenague Level 7 Level 7 (32,955 points)

    Sorry but it can be an issue even with one computer and the TC.. it is not the fault of the using multiple computers doing backups.. it is a fundamental network flaw. The computers have lost the connection to the disk for some reason.


    But your experience is interesting.. backup to the internal disk.. which is only from your laptop is at least statistically related.. as I put together your post that is what I am reading.. with other computers using the external drive plugged into the TC having no trouble.. you could be onto something.


    Can I suggest you start a new backup for your laptop somewhere else.. if there is enough space to the external disk as well but perhaps better not the TC at all.. use a usb drive plugged in.. for just another week or so.. it will just be a trial.


    Does the internal disk of the TC have a name with a space.. eg Time Capsule .. not a simple name like data.. apple seem to have used both.


    What OS is on all the computers?

  • LaPastenague Level 7 Level 7 (32,955 points)

    Thanks for good diagnosis.. that is useful.


    There is certainly an issue where the computer is not closing off the backup correctly and dismounting the sparsebundle. That is required so the next time the disk is available. That is why the reboot or the disconnect all users works.. it is forcing the sparsebundle to dismount.. so TM can then remount it as it needs to do to start a backup.


    What OS is on all the computers?


    What OS particularly is on the laptop that has no issues?


    It is definitely worse on Mountain Lion than anything else.. The issue began with Lion.


    I use Snow Leopoard.. (and occasionally a laptop on ML).. and the SL computer has no problem with TC running older firmware.. none.. rock solid stable. But as soon as I flash the TC up to current firmware level.. within a day the SL computer starts having server disconnect issues.


    Apple changed the security level of AFP in Lion.. which required the firmware update in TC. The end result has never been a happy one.


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